Interaction effects of arrays of sonar transducers

To radiate at high power for an array of limited size it may be necessary to have closely spaced transducers. If the transducers are half a wavelength or closer there is likey to be significant interaction effects between neighbouring transducers. It is then necessary to include mutual impedance effects in predictions of response. Fully coupled finite/boundary element analysis will naturally include such effects.

Radiation from line array of ring transducers

The pictures below show the animated pressure field around a line array of DERA test ring transducers, from fully coupled FE/BE analysis in PAFEC VibroAcoustics, using a model supplied by the sonar department at DERA Winfrith. An axisymmetric mesh was used. The lower line is the axis of symmetry. It can be seen that the level of damping in the transducers affects the interaction.

The outer transducers are doing most of the work in radiating the field.

Damped case (different scaling for contours)
There is a much more even output from the transducers

A detailed description of the transducers and further information on the modelling is contained in the paper "Performance prediction of an array of free flooding ring transducers", A.B.Gallaher, Sonar Transducers '95, Proc I.o.A. Vol 17 Part 3, pp 34-43, 1995